Method of cutting shingles



F'eB. 23, 1932. D. FINLEY 1,846,635

METHOD OF CUTTING SHING'LES Original Filed May 2. 1927 0021s.? Fla/45v em/J. 664% HIS ATTORNEY INVENT OR Patented Feb. 23, 1932 UNITED STATES PATENT OFFICE DOZIER I'INLEY, OI BERKELEY, CALIFORNIA, ASSIGNOB TO THE PARAFFINE COM- PANIES, INQ, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF DELAWARE METHOD OF CUTTING SHINGLES Original application filed May 2, 1927, Serial No. 188,129. Divided and this application filed January 14, 1930. Serial No. 420,737.

My invention relates to shingles and especially to a method of cutting shingles out without waste from a parent sheet of prepared roofing. This application is a division of my co-pending application Serial No.

188,129, filed May 2, 1927.

Another object of the invention is to produce in a single cutting operation two variant forms of a single type of shingle, such that the two forms, tho of different shape, may

be used together and interchangeably, and

also independently.

Another object of the invention is the cutting of shingles in such a manner that direct wastage of one portion of the parent sheet fixes upon another phase of the cutting operation a condition by which another portion of the parent sheet, larger than the wasted portion, is usefully conserved.

Another object is to produce at a single cutting operation two shingles of the sametype and of equal exposure, in which different quantities of the parent material are used, whereby two different pecuniary values are automatically made to attach to things of the same ultimate superficial appearance.

My invention possesses other objects and features of advantage some of which with the foregoing will be set forth in the following description of my invention which is illustrated in the drawings forming part of the specification. It is to be understood that I do not limit myself to the showing made by the said description and drawings as I may 7 adopt variant forms of my invention within the scope of the claim.

Referring to the drawings Figures 1 and 2 are, respectively, plan views of the unlike shingle units embodying my invention.

Figure 3 is a plan view of a portion of a parent sheet, showing the shingle units in the cutting position and before the separation of the units.

Figure 4 is a plan view of a portion of a roof formed with my shingle, showing the interchangeability of the two forms.

Figure 5 is a plan view of a modified form of the shingle unit shown in Figure 1.

In the manufacture of shingles from a parent sheet of prepared roofing, it is obvious that wastage of material is a vital factor in the design. It is also obvious that there is a very high value in any method of cutting which permits a greater number of shingles to be cut from a given area of parent material. Heretofore in the art, ithas been the custom in producing the so-called hexagonal strip shingle, to run a zigzag cut longitudinally thru an elongated strip of roofing material, the zigzag out being reversely symmetrical around the axis of the elongated strip and generally speaking having inclined portions crossing the axial line at about 60 degrees thereto and having parallel portions alternating with the inclined portions and of approximately equal length.

Shingles formed in this manner can be laid by lapping one over the other in such a manner that a projecting tongue formed by the zigzag cut on the overlying shingle will match with a recess of the under shingle. If the dimensions are properly chosen, it will be found that'a series of such shingles laid in this manner will not only cover an area completely but that there will be a lap at every point suflicient to prevent falling rain from reaching the underlying structure, providing ofcourse that there is a cooperating slope to assist in the rapid carrying ofi of the water.

It will be found however that the amount of the usual lap varies widely. At the minimum point, it may be as little as one-third of the amount at the maximum point.- In general, at the maximum, it may be expressed as equivalent to the length of a projected tongue formed by the zigzag cut plus a fixed amou t. If the minimum amount of lap determined by the fixed amount, is sufiicient to insure weatherproofness on the roof covered, it is obvious that there is an unnecessary usage of material in those arts of the lap which materially exceed t e minimum. Material thus needlessly used should be constructively diverted to the useful purpose of weather exposure or the equally essential purpose of use in the necessary laps which go with each exposed portion.

In order to make use of the parent sheet of material most economically, it has been found that where four or a higher even number of shingle strips are cut transversely of the sheet, it is possible to notch what will be the upper, or nominally straight edge of the shingles. The notches on the pair of shingle strips cut from the center of the parent sheet are dovetailed together, that is, the edges are complementary.- The shingle strips cut from the outside edges of the parent sheet have no mate with which they may be dovetailed on the outer edges and therefore notches cut from these outer edges will result in wasted material. It is found however that the amount of such wastage is less than the amount conserved by the dovetailed notching of the two inner strips.

In the drawings I have shown a parent sheet divided transversely into four shingle strips, but it will be clear that the economy of my method of cutting, increases as the number of such stri s increases. It is understood that the num er of shingles measured transversely of the parent sheet will always e even.

A mathematical expression for calculating the dimensions, area and cutting constants of any particular type of shingle involving this principle follows:

a=number of shingle strips which will have an aggregate area of 100 square feet of furface exposed to the weather when a1 b=width of the parent sheet in inches. c=length of each shingle strip in inches.

=number of shingle strips in a single section of the parent sheet taken transversely (always an even number). e= depth of notches in the notched upper edge of the strip, in inches. 1 f=lap at upper edge of hexagon when laid (least lap) in inches. exposed area of each a square feet, or

a =exposed area m square lnches.

14400 etfective width (average width) of ac each shingle strip exposed to weather.

shingle strip in Since the shingle strips are complementary, the area exposed by the notch of an overlying shingle is equal in area and similar in shape to the area covered by the tab; therefore the matched relation.

extreme width of the shingle is twice the average exposed width plus the overlap, or

28800 extreme width of a single shingle ac strip.

2d; therefore a pair of interlocked (d=2) shingles will have an extreme width of but where d is 4 then 21600d ac Where (i is greater than 4 21600d @(d-2) (3) T T The general formula (3) satisfies the conditions of the specific cases in (1) and (2).

It will be noted that the form of the cut which forms the shingle tabs is not material to this formula as the only factors of the formula concerning the shingle tabs are the number of shingles required to cover one square and the length of each individual shingle, which two factors automatically determine the average width exposed. Beyond that, any number or shape of tabs can be chosen so long as they can be cut in The same applies to the notches at the top of the shingle.

There is a factor in the formula, however, which does not appear in the above statement, and this concerns the shape of the tabs and the notches at the top. If e is considerably greater than f or, in some cases, if it is only nearly as great as f it will be found that the distance from some one (the nearest) portion of the exposed surface of an underly: ing shingle t0 the edge of some one (the nearest) part of the notched portion of the top edge of the same shingle is less than f-in which event the calculation must either be repeated, assigning a smaller value to e or a greater value to f, or else it may be found only ed that these shingles will be cut on a machine which forms the sub'ect matter of a co-pending application Senal Number 627,496. It will also be understood that I may, or may not, notch the shingles cut from the outer strip of the parent sheet, along their nominally straight upper edges. That is, I may cut all of the parent material into {shingle units similar totha't shown in Figure 1. Thus if four shingle strips are made across the parent sheet, the form of shingle shown in Figure 1, can be produced in any amount from 50 to 100 percent of the arent sheet, and the other form shown in igure 2 may be produced in any amount from 0 to 50 percent of the total.

, In Figure?) of the drawings, I have shown the proportions of typical shingle units, embodying my invention. In this example the shingles are cut from a parent sheet of roofing material inwhich values may be assigned as follows:

With the dimensions indicated it will be found that 84 shingles can be cut from 181 square feet of parent material. This will be sufiicient to cover one square with an average efiective exposure of each shingle of about 5". and a minimum lap of about 2".

Where'the shingles are cut in such proportions that those of the form shown in Figure 1 are produced in numbers equal to those shown in Figure 2, only 17 2.4 square feet of material will have been used in cutting 84 of the Figure 1 form; and 189.6 square feet'of the parent sheet will have been used in cutting 84 of the Figure 2 form. From this it appears that 17.2

square feet more of material is employed in the Figure 2 variation than in the Figure 1 variation, per square of finished roofing. If equal quantities of the forms shown in Figures 1 and 2, are cut from the parent strip, the gross saving of material is represented by the difference between 181 square feet and 189.6 square feet, that is, a saving of 8.6 square feet of parent material to each square ofroofing.

That the economies thus effected-are very real, and may be reflected in materially lower selling costs of the product, needs no argument. A further economy lies in the fact that in the shingle shown in Figure 1 there is 9% less material by weight, than in the shingle shown in Figure 2, and this represents an additional economy and advantage in the matter of freight charges, especially when shipments are made for a considerable distance.

' Referring particularly to Figure 3, the parent sheet of roofing material is separated into four longitudinally extending shingle strips by outs defined by the zigzag lines 6, 7 and 8. With the parent sheet divided into four shingle strips, there will be three such zigzag lines, and each will be reversely symmetrical about a longitudinally extending axis. The zigzag line 6 is reversely symmetrical about the axis 9; the zigzag line 7 is reversely symmetrical about the axis 11; and the zigzag line 8 is reversely symmetrical about the axis 12. It will be noted that the central or inner axis .11, extends down the center of the parent sheet, and that the axes 9 and 12 are evenly spaced on each side of the central axis. If each of the shingles shown in Figures 1 and 2 is to be made in equal quantities from the parent sheet, the outer edges are left straight so that the back or upper edge 13 of the shingle when laid, comprises a substantialy straight line as indicated in Figure-2. If all of the shingles to be cut from the parent sheet are to be formed as shown invFigure 1, notches 14, defined by the broken line 16 are formed in the outer edges and it will be noted that the boundary edge thus formed comprises a broken line reversely symmetrical about the longitudinally extending axis 17; that this broken line is identical with the broken line 7 and that the axis 17 is spaced the same distance from the axis 9, that the latter is from the central axis 11.

It will also be noted that the central zigzag line 7 is comprised of parallel portions 21 and 22 connected by transversely extending portions 23 and 24; and that the zigzag lines 6 and 8 are of the same character, difi'ering only in the length of the parallel and the transverse portions."

' From the above it will be understood that the parent sheet is divided into an even number of shingle strips, which in the cutting position dovetail together or are complementary to each other along contiguous edges. It will also be seen that all of these strips may be identical'or that there may be like pairs of unlike strips, but man cases there is one edge, the exposed edge when the shingle is laid and defined by the lines 6 and 8, which is identical in all units.

At intervals the shingle strips are severed into the separate units by transversely extending cuts defined by the lines 28, which, as to any one group of shingles extending across the parent sheet are staggered. Preferaly these transverse cuts are perpendicular to the longitudinal axis of the sheet but this isnot necessarily so; and in Figure 5 a different relationship is shown.

In Figure 4 is shown a section of roof laid with my shingles and showing both variant forms, notched back as shown in Figure 1, and straight back as shown in Figure 2, laid interchangeably. While circumstances would ordinarilyv prevent the mixing up of the two forms of shingles in this manner, it might happen; and so far as usefulness and suitability are concerned, the two forms of shingles are entirely interchangeable, it being noted that the structural differences are concealed in the laying position and that the exposed portions of both forms are identical. It will also be noted that the lap f is preserved at the desired value when the shlngles are laid irrespective of the t pe of shingle used.

In Fi ure 5, have shown a variant form of the s in le illustrated in Figure 1. This shingle di ers from the type s own in Figurel, chiefly by its rounded corners, the parallel portions 31 and 32 of the weather exposed edge. merging into the transverse portions 33 and 34 in the curves 36. The boundary edges of this shingle are thus formed of broken lines in which the corners are smoothed into curves.

This form of shingle has some advanta es because the rounded corners result in a slightly increased lap at the corner. Consequently the notching of the back edge may be made deeper to bring this lap back to the minimum amount, thus securing an additional economy of material.

I claim:

The step in the method of cutting from a parent sheet and with minimum waste of material shingles having normally exposed semi-hexagonally shaped tabs, which com-i prises separating the parent sheet into strips by a plurality and uneven number of longitudinally extending cuts, each out being defined by a broken line comprising parallel portions alternating with transversely extending portions and reversely symmetrical to a longitudinally extending axls, said cuts comprising alternate cuts forming the normally exposed edges of said shingles in which the parallel portions are of substantially equal length and the out between said alternate cuts forming the normally unexposed edges of said shingles in which the parallel portions are of substantially equal length, the transversely extending portions of the cut between said alternate cuts being of lesser length than the transversely extending portions of the alternate cuts.

In testimony whereof, I have hereunto set my hand.

DOZIER FINLEY. 

